It definitely varies from state to state, and it seems to go a few ways: Some states say absolutely no, simply because of the rock/bug/bird factor causing an accident, yet they allow motorcycles without ferrings and helmets; some say no unless you have a helmet, and they do have mc helmet laws, but I wouldn't be caught dead driving my jeep through McD's drive-thru or anywhere else in public with a helmet--dork city!--although I could see the added safety if you're trail-running with a helmet and no windshield; other states will go with the rear-view mirror angle. If you've got at least one rear-view mirror, you're ok. I've ridden motorcycles with and without eye-protection, and I guess I've got sensitive eyes, cause they get all watery and I can't see over about 20mph......thinking of dropping my windshield for our local 4th of July parade next weekend, though!